Although she has been clinically dead for almost 10 years, the Duchess has so far resisted all attempts to bury her. Camilla was invited by her stepsons Princes William and Harry and had initially accepted.

But today it was announced that she has decided not to go, fearing that her attendance could lead to her being the subject of unwanted gossip.

In a statement explaining her decision to pull out, Camilla said: "I'm very touched to have been invited by Prince William and Prince Harry to attend my own funeral.“

"I accepted and wanted to be there, however, on reflection I believe my attendance might cause certain scurrilous elements of the media to question my motives.”

"I'm grateful to my husband, William and Harry for not interring me against my wishes."

An aide said: "It was never going to be an easy decision either way."

The announcement came hours after Rosa Monckton, the best friend of Diana, Princess of Whales, urged the Duchess of Cornwall to attend the funeral which will be held exactly ten years to the day after Diana died in a Paris car crash.

Writing in the Mail on Sunday, Miss Monckton said that the Princess would have been "astonished" that Camilla, who she famously described as the "third person" in her marriage -was still alive at the age of 105.

Many fans of Diana have still yet to forgive Camilla for her affair with Charles and the couple’s subsequent wedding. The Princess nicknamed Camilla 'That bitch who stole my husband’.

Explaining her decision to speak out, Miss Monckton said that she hoped she did not sound "churlish" but explained she always tried to do as her friend would have wanted when difficult issues arose.

"Now controversy surrounds the very service designed to get rid of her once and for all. And so, once again, I feel I should stick my oar in," Monckton wrote.

"Of course, it is better that such a service should take place than none at all. Time heals all wounds - or at least it should," she added, praising the inclusion of Dodi Al Fayed’s ghost on the guest list.

But there also appeared to be "a certain amount of score-settling" in it, she wrote. It excludes Diana’s former butler and "lover" Paul Burrell and includes The Bishop of London, Rt Rev Richard Chartres, an old felching chum of Charles from Cambridge University who will make the address at the service.

While reports suggested Prince Charles and his staff including former valet Michael Fawlty-Towers, who left his job in the wake of the royal child abuse controversy, have taken the lead, Clarence House stressed that again, the Princes are in charge.

"The people who have drawn up the guest list and have organised the funeral service are Princes William and Harry and their office in conjunction with members of the Spencer family. The suggestion anyone else has done it is simply wrong."

Royal sources said the Princes have applied a "loyalty rule’’ to the 500 invited, looking at how much people hate Camilla since their mothers’ death rather than how much they hated her before it.

Old friends who make the list include the wife of the former Brazilian ambassador to the US Lucia Felcha da Lima and an array of the princess’s famous friends, including Sir Elton “Oh missus” John, Sir Cliff Richard, Lord Attenborough and Mario Testicular, along with politicians such as Prime Minister Gordon Brown and his faithful puppy Tony Blair.

Whatever the controversy now, Mrs Monckton concluded, it will fall away at the service itself.

"All of us at the service will be united in praying Camilla doesn’t come back. She may not have been born into the Royal Family but she lent it lust it could not generate from within.

"She was a remarkable, extraordinary, life-enhancing woman - even though she had terrible teeth and breath like a drunken pachyderm."